Williams-Sonoma Inc. has felt as safe as houses lately. But the shelter may not last.

Shares of the upscale home-furnishing retailer have risen 36% this year as new housing construction and signs of economic recovery sparked demand for furniture. The big winner has been Pottery Barn, Williams-Sonoma's largest division with about 43% of group revenue. Its sales rose a healthy 7.6% from a year earlier in the fiscal first quarter ended...